The present invention relates to reducing the failure of a system that carries electrical, optical, or electromagnetic (as in waveguide) signals or that conveys fluids. In particular, it relates to failures of such a system that result from chafing of the conduits within it. Such a system may carry electrical power; fuel, refrigerant, other fluid; or optical and/or electromagnetic signals. Or the system may be hydraulic or pneumatic. Degradation or failure of such a system could also expose the systems around the conduit to adverse effects, as when a spark ignites the contents of a fuel container.
The outer surfaces of electrical, optical, and electromagnetic cables and cable bundles are frequently subject to wear caused by rubbing against external structures. If allowed to proceed, this wear can cause grounding, shorting, or breaking of the cable's internal structures (conductors or optical fibers). Hydraulic, pneumatic, and fuel or other fluid lines, pipes, and hoses are also susceptible to failure from chafing.
Each of these structures susceptible to chafing can be called a "conduit". This application uses the term conduit for any structure that can fail from chafing, such as a cable, cable bundle, hydraulic hose or pipe, pneumatic hose or pipe, or fuel/fluid hose or pipe.
A conduit often fails before a system's operator knows that the conduit has a chafing problem. Currently nothing is in wide use to detect when a conduit experiences chafing and thus becomes subject to failure. The disclosure of U. S. Pat. No. 4,988,949 is limited to detecting chafing on electrical cables against an electrically grounded structure under constant monitoring. It teaches nothing about either periodic testing or detecting chafing on any conduits other than electrical cables, nor does it detect chafing against a non-electrically grounded structure.
Thus there exists a need for a simpler apparatus and method of detecting chafing on any conduit that is likely to chafe against a non-electrically grounded structure or that requires only periodic monitoring.